1. FIeld of the Invention
The present invention relates to a magnetic powder for a magnetic recording medium having improved magnetic characteristics.
2. Description of the Prior Arts
Acicular iron oxide powders have been mainly produced as a magnetic powder for a magnetic recording medium.
Home video tape recorders (VTR) have been developed and high quality audio cassette tapes have been commerciallized. Density of recorded signal required for a magnetic recording medium has been increased. Such high density of the magnetic recording could not be attained by using the conventional acicular iron oxide. Various magnetic powders having high coercive force and high magnetic flux density have been developed.
A magnetic powder having high coercive force having improved crystalline magnetic anisotropy obtained by coating a solid solution of cobalt component on the acicular magnetic iron oxide powder has been studied as one of the improved magnetic powders. The magnetic powder has, however, disadvantages of high temperature dependency of magnetic characteristics and high demagnetization under pressure and high demagnetization by reproducing in repeated running in a tape and large printing effect. Therefore, it has not been practically used.